Northern Lights Now – The expected ICME has arrived. In the first hour since it arrived, solar wind data is indicating that is is oriented favorably to put on an aurora show.
Update: 16:00 GMT Oct 12, 2021:
What an amazing storm! The third phase of the storm arrived around 9:30 and had a strong (-14nT) southward component. With the atmosphere already primed from the first phase of the storm, aurora activity quickly elevated. Aurora sighting reports rolled in from all across northern North America. NLN will be doing storm recap later, but for now, enjoy this timelapse that shows all three phases of the storm from skunkbayweather.com
Awesome #AuroraBorealis last night. @NWSSeattle @ScottSeattleWx @ShannonODKOMO @KClarkWx @CraigHerreraTV @Rebecca_Weather @NickAllardKIRO7 @MorganKIRO7 @WxVillegas @ErinMayovsky @TamithaSkov @timdurkan @WeatherNation @wxchanneldesk
— Skunkbayweather (@Skunkbayweather) October 12, 2021
Update: 08:00 GMT on Oct 12, 2021:
It appears the second part of the CME is arriving, and Bz orientation is variable. It’s likely this means the storm is over for now.
Update: 07:00 GMT on Oct 12, 2021:
This has been a terrific storm. There has been an extended (6 hours now) period of moderate activity. Aurora reports have been coming in on Twitter from Iceland, Canada, New England (as far south as southern New Hampshire), the mid-west US and now Washington State and Alaska. Geomagnetic activity has reached G2, KP=6, levels as predicted by the SWPC.
The show looks like it will continue. Bz just dropped strongly south, so there should be another sub-storm over the next hour or two. We are expecting there will be aurora reports streaming in from hunters in New Zealand and Tasmania next.
After the current sub-storm, expect the core of the CME to arrive at earth. It is still impossible to forecast the orientation of the core of this storm. It is about a 50/50 tossup that it is oriented south and there is another 6-9 hours of activity, or that it is oriented north and the aurora ends. Keep an eye on the data and the orientation should reveal itself soon.
The shock arrived at the DSCOVR satellite around 1:45am GMT on October 12, 2021. At the time of impact, Solar wind speed jumped from 350km/s to almost 500 km/s. Proton density and BT also jumped in synchrony. Bz is always the wildcard. It is hard to know how the B component will be oriented until it arrives. Tonight, it arrived with a strong negative orientation. This is the most favorable setup for producing aurora.
In the image below, the upper chart is a proxy for hemispheric power and can be seen on the DSCOVR solar wind page. The more bars and the longer the bars the higher the likelihood of aurora. As time goes on, if the favorable conditions persist, the bars will continue to grow. In the lower part of the image, you can see when the ICME shock arrived with the big jump in solar wind data.